The csswg is a W3C working group. It's true that there are sometimes breaking changes if usage is low enough. This is true of the W3C specs as much as it is of

The csswg is a W3C working group. It's true that there are sometimes breaking changes if usage is low enough. This is true of the W3C specs as much as it is of the WHATWG specs. The advantage to following the WHATWG specs is that it reflects how browsers work today, not how they worked a few years ago.